Chapter 6, Problem 78E

Interpretation Introduction

Interpretation:

The enthalpy change $\text{ΔH}$ of given reaction has to be calculated and the feasibility of ammonia synthesis should be discussed.

Concept Introduction:

Hess's Law:

• The changing enthalpy of a chemical is self-determining of the route by which the chemical reaction occurs.

• The enthalpy change of the reaction is equal to in which reaction is occurs whether it is in one or multiple steps.

• Formula:

• $\text{ΔH}\left(\text{total}\right)\text{= }{\displaystyle \sum \text{ΔH}}\left(\text{number of steps}\right)\mathrm{......}\text{(1)}$

Rules:

• The sign of $\text{ΔH}$ reversed when the reaction is reversed.

• The quantities of reactants and products are directly proportional to the magnitude of ΔH in a reaction. If the coefficients in a balanced reaction are multiplied by an integer, the value of $\text{ΔH}$ is multiplied by the same integer.